1. For the starter mixture, mix the white flour, wholemeal flour, rye flour and dried yeast together in a large mixing bowl until combined. Add the warm water, stir until well combined, but do not overwork the mixture, then cover the bowl tightly with cling film and leave in a warm, draught-free place for at least six hours, or overnight, to ferment.

2. For the bread, mix the white flour, wholemeal flour, warm water and salt with the fermented starter mixture until well combined, then bring the mixture together to form a dough.

3. Turn out the dough onto a clean, floured work surface and knead with floured hands for 15-20 minutes, or until smooth and elastic. Shape the dough into one large loaf or two small cobs.

Transfer the loaf to a baking tray, cover with cling film and set aside for two hours, until doubled in size.

4. Meanwhile, preheat the oven to 230C/450F/Gas 8. Once the loaf has expanded, brush the top of it with the beaten egg and sprinkle with the porridge oats.

5. Bake the loaf in the oven for 25-30 minutes, or until cooked through (the loaf is cooked when it is risen and golden and sounds hollow when tapped underneath).